Compounds identified by the Drug Synthesis and Chemistry and Chemistry Branch for testing in the NCI's anti HIV and antitumor screens consist variously of voluntarily donated compounds and those which are requested from their authors from the published recent literature on the basis of their structural novelty or relevance. Compounds in this last category are often not available to the program. Situations also arise where follow up testing of a lead is precluded by the fact that the original donor cannot provide additional sample or a small series of structurally related compounds. This service project provides for the preparation of these organic or inorganic compounds required by the screening and development programs. As many as 200 compounds may be assigned to the contractors over the life of this project. The scale of the work will typically involve a request for samples of final compounds in the range of 100 mg to 5 grams. Specific experimental conditions from the published literature will be available in the majority of cases. Some process development may be required in instances where detailed procedures are not reliable or are unavailable. The contract mechanism is deemed the most appropriate instrument for fulfilling the requirement because: The compounds to be acquired are not stock catalogue items; successful preparation of the assigned compounds will require significant technical direction by the Project Officer. A contract allows for the acquisition of the compounds on a priority basis and time frame controlled by the Government, for the direct benefit or use of the Government.